Are there any films with a 10/10 rating on IMDb?

I haven't noticed feature films with 10. There are plenty of TV episodes and short films with 10. They have a very small band of fans that often give every episode or short 10 every time. IMDb don't publicize a rating till a film has got 5 votes which should urge a failsafe way of not having too many films with 10. Any feature that has become popular over the years is never going to have a 10 rating because of the great amount of votes. You can't please all the people and I should think there a good few fans who never give a 10 for a movie.

A better question might be, are there any 9's that are actually somewhat popular.

The only 9.x are movies from India. Most have under 1,000 votes.

imo really great films are going to be necessarily challenging and therefore escape/turn off some portion of the viewing audience.

How many people read great novels, or enjoy them even if trying ?

Well, would you look at that. A new movie tops the chart:

https://i.redd.it/bs3xaxo6q2m91.png

I've seen the whole film, and it's certainly a masterwork that no trailer could truly encapsulate:

https://youtu.be/837UfNITVPo

Yes, lots. But they seem to have very few votes and I'm guessing almost no one has heard of them.
https://www.imdb.com/search/title/?title_type=feature&user_rating=10.0